Minarc Evo 150 Service Manual

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Kemppi Oy

SERVICE MANUALMinarc Evo 150


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CONTENTS

1. READ THIS FIRST ........................................................................................................................................... 1

2. GENERAL......................................................................................................................................................... 2

3. TECHNICAL INFORMATION ........................................................................................................................... 3

3.1. Technical data ........................................................................................................................................... 33.2. Wiring diagrams ........................................................................................................................................ 43.3. Construction .............................................................................................................................................. 5

3.3.1. Inner structure .................................................................................................................................... 63.3.2. Z001 main circuit card structure ........................................................................................................ 73.3.3. A001 control card structure................................................................................................................ 8

3.4. Description of operation ............................................................................................................................ 93.4.1. Z001 Main circuit card ....................................................................................................................... 93.4.2. A001 Control card ............................................................................................................................ 10

4. SERVICE INSTRUCTIONS ............................................................................................................................ 12

4.1. Programming ........................................................................................................................................... 124.2. Calibration ............................................................................................................................................... 12

4.2.1. Functions and buttons ..................................................................................................................... 124.2.2. Calibration parameters .................................................................................................................... 154.2.3. Calibration procedure ...................................................................................................................... 15

4.3. Measurements and tests ......................................................................................................................... 164.3.1. Z001 Main circuit card ..................................................................................................................... 16

4.3.1.1. Input rectifier and PFC circuit ................................................................................................... 174.3.1.2. IGBT ......................................................................................................................................... 194.3.1.3. Secondary rectifier.................................................................................................................... 214.3.1.4. Voltages .................................................................................................................................... 214.3.1.5. Overheat protection .................................................................................................................. 23

4.3.2. A001 control card ............................................................................................................................. 24

4.3.3. Cooling fan ....................................................................................................................................... 254.3.4. Low voltage tests ............................................................................................................................. 254.3.5. Safety tests ...................................................................................................................................... 26

4.4. Semiconductor installation ...................................................................................................................... 264.4.1. Rectifier/PFC module and IGBT ...................................................................................................... 264.4.2. Secondary rectifier ........................................................................................................................... 27

4.5. Final testing ............................................................................................................................................. 274.5.1. Load bank test ................................................................................................................................. 284.5.2. Test welding ..................................................................................................................................... 28

5. NOTES ........................................................................................................................................................... 29

APPENDIX


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Service manual Minarc Evo 150 Version 1.1.3. 15.3.2012

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1. READ THIS FIRST

230VAC 50/60Hz and 390VDC or higher are inside the machine

Before removing any covers or commencing any testing or measurement disconnect the power sourcefrom the mains voltage

Dangerous DC voltage may still exist after the removal of the input voltage. Machine discharges thevoltage while it is turned off, but it is always better to ensure this by measuring the voltage

Wait at least one minute for the capacitors to become discharged.

Digital multimeters (later DMM) may give different values depending the specifications they have. Forexample diode measuring values may vary between the DMM models. In this manual Fluke 179 DMM isused.

This machine has all the control circuits in the primary side and special attention must be consideredwhile working with the internal parts.

The device may be repaired only by a person legally authorized to perform electric work.


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2. GENERAL

Minarc Evo is new generation small MMA machine. It is not based on any existing machine. It is totallynew design electrically and mechanically. Machine has a power factor correction in the primary side to

meet the latest European regulations.

The Minarc Evo machines are for MMA-welding and lift-TIG can be used as well. MMA open circuitvoltage is 90VDC or 30VDC with VRD activated.

Minarc Evo can be connected to the mains supply of 230VAC 1~. PFC makes possible to weld with thefull power (MMA 140A) even when modern circuit breakers are used.

Minarc Evo control card software cannot be reprogrammed in the field.

Overvoltage watch is 300VAC and under voltage watch is 110VAC; voltage must be increased back to160VAC to get the inverter back to full operation after the under voltage situation.

Current range is 10-140A in MMA and 10-150A in TIG mode.

Minarc Evo discharges the DC link voltage after switching the main switch off by running the cooling fanas long as the control electronics is wake.


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3. TECHNICAL INFORMATION

3.1. Technical data

Minarc Evo 150Connection voltage 1~50/60 Hz 230V 15%Rated power 35 % ED MMA 140 A/4.5 kVA

35 % ED TIG 150 A/ 3.2 kVASupply current

35 % ED I max1 19.7 A

100 % ED I eff1 12.9 A

Connection cable HO7RN-F3G1.5 (1.5mm

2, 3m)

Fuse Type C 16A: 140A ED 35%10A: 140A ED 28%

Duty cycle 40C 35 % ED MMA 140 A/25.6 V100 % ED 100 A/24.0 V35 % ED TIG 150 A/16.0 V100 % ED 110 A/14.4 V

Welding range MMA 10 A/15 V - 140 A/37 VTIG 10 A/1 V - 150 A/36 V

No-load voltage; peak 90 V (VRD 30V)Idle power 17 WVoltage steps steplessPower factor at 100 % ED 0.99Efficiency at 100 % ED MMA 82 %Stick electrodes 1.5mm 3.25 mm, and

some 4mmExternal dimensions LxWxH Height with handle 361x139x267 mmWeight Without connection cable 5.4 kg

With connection cable 5.85 kg

Temperature class B (130 C)EMC class ADegree of protection IP23SOperating temperature range -20+40 CStorage temperature range -20+60 CStandardsIEC60974-1IEC60974-10IEC60974-3-12


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3.2. Wiring diagrams

Latest version with better quality is available at Kemppi Channel.


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3.3. Construction

The cooling fan is installed so that the air flows from the left side plate to Z001 card. Air comes outthrough the front and the back plate grills.

Left sideFront

Right side Back

Left side, side plateremoved Left side plate withcooling fan


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3.3.1. Inner structure

1. Main switch2. Primary heat sink3. T001 main transformer4. Secondary heat sink5. Secondary choke6. Remote control socket7. A001 control card8. Z001 main circuit card

1.

2.3. 4. 5.

7.

6.

8.


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3.3.2. Z001 main circuit card structure

1.

2.

3.

4.5.

6.

7.

9.

8.

1. Primary rectifier and PFC module2. IGBT module3. DC-link capacitors4. Main transformer5. Secondary diodes, zero side + stress reduction resistor6. Negative output connector7. Positive output connection8. Secondary diodes, positive side9. X9 connector to A001 card10. PFC choke

10.


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3.3.3. A001 control card structure

1. X2 service connector (not field programmable, serial busconnection is in the primary side)

2. MMA/TIG selection3. Remote ON/OFF4. Microcontroller5. Analogic potentiometer6. 7-segment display7. X1 connector to main circuit card (flat cable)8. Overheat LED9. VRD LED10. Welding machine ON LED11. TIG mode LED12. MMA mode LED13. Remote ON LED

1.

2.

3.

4. 5.

6.

7.

8.9.10.

11.

13.

12.


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3.4. Description of operation

Minarc Evo 150 can be divided to two parts: Z001 main circuit card and A001 control/panel card

Z001 main circuit card

o Input rectifier and PFC circuito IGBT moduleo Main transformero Secondary rectifiero Secondary chokeo Auxiliary switching power supplieso Current measuring

A001 control card

o Inverter controlo Panel displayo Current set value adjustmento Panel buttons functionso Panel LEDso Remote control functions

3.4.1. Z001 Main circuit card

Main circuit card; coil components and their functions:

Main transformer turn ratio is 4:1; its primary winding is 20 turns (wire) and secondary5 (foil). Transformer has 140C PTC for over heat protection. While temperature risesthe resistance stays under the 100until the breakdown point (140C), then the PTCgoes to high-resistance mode (>10k). Control logic stops inverter when theresistance value rises over the 1,5k.

Secondary choke L3 inductance is 5H and its winding has13 turns. Choke slows thesecondary voltage changes and works as energy storage in the long short circuits.

PFC choke works together with PFC circuit. It has 66 turns.

Main circuit card itself provides the following functions:

DC-link soft start charging and over voltage protection circuit. It avoids full powerconnection if the primary has a short circuit or main supply voltage rises over thesafety limit.

EMC filtering circuit filters EMC disturbances from main supply voltage to machineand vice versa.

The single-phase rectifier/PFC module rectifies the mains voltage (nominal 230VAC)to PFC circuit, approx. nominal value of 320VDC. Rectifier holds four power diodes.

PFC circuit is integrated in the same module with rectifier diodes. PFC circuit (twoparallel IGBTs, two diodes in series and PFC choke) keeps the primary voltage andcurrent in the same phase. This rises the power factor up to 0,99. PFC is boost typeand raises the DC-link voltage up to 390VDC.

Power section is based on dual forward architecture with 63 kHz switching frequency.It has two stages: ON and OFF/demagnetizing. OFF-stage must last longer time thanON-stage because main transformer needs to be demagnetized. Otherwise it goes tosaturation.


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Both modules have integrated NTC resistors for over heat protection: In 0-40Cenvironment temperature range, resistance varies between the 60-15kif themachine is cool. In the overheat situation NTC resistance lowers down to 2kandeven lower. Machine stops the inverter in the 2kpoint. Note that NTC has

descending nominal curve: When temperature rises resistance lowers. Z001 card has an auxiliary power supply which delivers auxiliary voltages to Z001

and A001 cards. Primary side: +16VDC for the upper IGBT gate buffer, floating+16VDC and floating GND for the lower IGBT gate buffer, and +24VDC for thecooling fan and charging relay. Secondary side: +12VDC (tolerance 1V) for theremote controller and reference GND.

o Note! Voltages are in the primary side (except +12VDC) so be careful whilemeasuring the voltages.

DC-link with two 470F electrolytic capacitors. Machine current is measured in theDC-link and feedback goes to the A001 card. DC-link is discharged by cooling fanwhile main switch is turned off.

Secondary rectifier has two working and three demagnetizing diode cases. Each

case holds two diodes so total quantity is doubled.

OCV (open circuit voltage) adjustment circuit keeps the voltage stable and at a safelevel.

Secondary shunt resistor is only for measuring the secondary current for thedisplays. Machine uses primary current measuring for inverter feedback.

Remote control connection circuit with galvanic isolation. Remote controller readingis in the A001 card.

Cooling fan control circuit. Control signal comes from the A001 card.

Dual forward inverter gate driver circuit. Control signal comes from the A001 card.

Secondary voltage monitoring in VRD mode. Limit is 32VDC and if voltage is higherVDR led is off in A001 card.

3.4.2. A001 Control card

Microcontroller controls e.g. current and voltage measuring and adjustment,protection circuits, remote control function, panel button function, panel LEDs,provides serial bus and saves calibration data.

o Note that calibration and service connection is in the primary side withoutgalvanic isolation. This is meant only for production use

Control card has control buttons for remote control ON/OFF and TIG/MMA selection.It has analogue potentiometer for welding current set value. These buttons andpotentiometer are used for the machine calibration also.

Card LEDs have following functions: Machine ON, TIG/MMA selected, overheatprotection ON and VRD activated. VRD LED lights only when it is activated, so in TIGmode and during the welding in MMA mode it is off.

7-segment display shows the current set value while not welding. During the weldingit shows actual welding current value. In calibration mode is shows the measuredcurrent value of machine.

A001 card has auxiliary voltages +16VCD (X1-1) and +24VDC (X1-2) from the Z001main circuit card PSU. A001 card makes +5VDC.


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o Note! Voltages are in the primary side so be careful while measuringthem.


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4. SERVICE INSTRUCTIONS

4.1. Programming

Minarc Evo 150 has a microprocessor on the A001 card. This can only be reprogrammed in Kemppiproduction because great care must be taken, because the connection is in the primary potential andwithout galvanic isolation.Normally there is no need for reprogramming, but in a special case, the only possibility is to fit areplacement control card that is factory programmed. In these cases please contact:[email protected]

4.2. Calibration

Minarc Evo must always be calibrated if an A001 control card or a Z001 main circuit card is replaced witha new one. Otherwise machine maximum/minimum current and/or panel display may be out of range.There are only two buttons and three LEDs to be used in calibration procedure. See the followingexample and guide on how to use the different functions in calibration mode.

4.2.1. Functions and buttons

To enter the calibration mode press and hold TIG/MMA and Remote buttons and switch on the machine.Keep pressing the buttons until calibration mode activated: On LED is pulsing at the rate 0,1s ON and0,9s OFF.

Picture1. Entering the calibration mode.

1. Press and holdboth buttons

Entering the calibration mode:

2. Switch onthe machine

3. ON LEDstarts blinking


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Moving from parameter to parameter can be done by combining the Remote ON/OFF and TIG/MMAbuttons in the following sequence.

Picture2. Moving between parameters.

Parameter 2: Current multiplier(150A)

Parameter 3: Display currentoffset min. (10A)

2. Press to go to the nextparameter

1. Press and hold

Moving to next parameter:

Parameter 2: Current multiplier(150A)

Parameter 3: Display current offsetmin. (10A)

2. Press to go to the next

parameter

1. Press and hold

Moving to previous parameter:


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Parameter values can be changed by using the buttons Remote ON/OFF and TIG/MMA separately.

Picrute3. Changing parameter value.

Increasing or decreasing the parameter value, affects the machine in different ways depending on theparameter. Example above is for illustration only, see the chapter Calibration procedure to get the stepby step instructions on how to proceed.

Parameter 3: Displaycurrent offset min. (10A)

Increasing the parameter value:

Parameter 3: Displaycurrent offset min. (10A)

Press to increase the parameter value

Press to decrease the parameter value


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4.2.2. Calibration parameters

Picture4. All calibration parameters.

4.2.3. Calibration procedure

If the parameter values go out of range or some other problems occur, use the parameter 0 to reset the

calibration data. Then it is easier to start from the beginning of calibration.

Switch off the machine and disconnect the welding cables

Enter the calibration mode (procedure on picture1)

Move to parameter 0 above (procedure on picture2)

Change its value (procedure on picture3). ON LED starts to cycle 0,9s ON and 0,1sOFF.

Once machine is switched off, restart the machine to get the parameter values reset.

Note! This parameter is only for resetting the calibration data; this is not the factory settings recall as inthe other Kemppi machines. After resetting the values, procedure must be carried out to ensure themachine working properly.

To get satisfactory and reliable calibration result welding current must be measured. A current clampmeter is easiest and accurate enough for this purpose. If a clamp meter is not available, a standard shuntresistor and multimeter can be used. In this case two welding cables are needed and the shunt should beconnected between them. Kemppi shunts have been stamped with the current-voltage relation, so it iseasy to use a standard multimeter with low voltage function (mV) for measuring the current value.

0. Reset the

calibration data(all LEDs off)

1. Current offset

min. (10A)

2. Current

multiplier (150A)

4. Displaycurrent multiplier(150A)

5. Remotecontroller offsetmin (10A)

6. Remotecontroller MMAmultiplier (140A)

7. Remotecontroller TIGmultiplier

(150A)(all LEDs on)

3. Display

current offsetmin. (10A)


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The following example uses a clamp meter. See the previous two chapters to study button configurations(Pictures 2 and 3) and parameter info (Picture4).

1. Switch off the machine. If a resistive load is available, this is the best option, connect the

resistive load via welding cables between the machine output Dix connectors. The ma-chine must be switched off to avoid arcing while connecting the cable. If a resistive loadis not available, it is possible to use a long welding cable (4 to 10 meters if possible) thelonger the cable the more accurate the current measuring.

2. Enter the calibration mode, ON LED starts plinking (procedure on picture1).

3. Move to the calibration parameter 1 (procedure on Picture2). Turn the potentiometer tominimum and check the measured current in the clamp meter value. Adjust parametervalue (procedure on Picture3) as close to 10A as possible, below 10A is better thanabove it.

4. Move to parameter 2 (procedure on Picture2). Turn the potentiometer to maximum andcheck the measured current in the clamp meter value. Adjust parameter value (procedureon Picture3) as close to 150A as possible, above 150A is better than below it.

5. Move to parameter 3 (procedure on Picture2). Turn the potentiometer to minimum andcheck the panel display value. Adjust parameter value (procedure on Picture3) as closeto 10A as possible, exact value is ideal. If this is not possible, select the one below 10A.

6. Move to parameter 4 (procedure on Picture2). Turn the potentiometer to maximum andcheck the panel display value. Adjust parameter value (procedure on Picture3) as closeto 150A as possible, exact value is ideal. If this is not possible, select the one above150A.

7. Switch off the machine, disconnect the welding cable or load and connect the remotecontroller.

8. Enter the calibration mode (procedure on Picture1) and move to parameter 5 (procedureon Picture2). Turn the remote controller potentiometer to minimum and check the paneldisplay value. Adjust parameter value (procedure on Picture3) so that it is three stepsbelow the point where it changes from 11A to 10A.

9. Move to parameter 6 (procedure on Picture2). Turn the remote controller potentiometer tomaximum and check panel display value. Adjust parameter value (procedure on Picture3)so that it is three steps above the point where it changes from 139A to 140A.

10. Move to parameter 7 (Picture2). Turn the remote controller potentiometer to maximumand check the current set value in the panel display. Adjust parameter value (procedureon Picture3) so that it is three steps above the point where it changes from 149A to 150A.

11. The calibration is now completed and once machine is switched off and restarted, theparameters are saved.

At this point it is good to check that the current set value can be adjusted from 10A to 140/150A with bothpanel potentiometer and remote controller.

4.3. Measurements and tests

4.3.1. Z001 Main circuit card

Power stage is divided in to two parts: rectif ier/PFC module and IGBT module. They can be testedseparately by using simply digital multimeter.


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4.3.1.1. Input rectifier and PFC circuit

Mains supply voltage must notbe connected during the rectifier/PFC module diode measuring.

In many cases of primary side failures input rectifier or the PFC circuit diodes may be broken. Rectifierdiodes can be measured one by one, but PFC circuit diodes only in two groups, because they areinternally connected parallel and in series. Two diodes between the PFC IGBT collector and emitter are inparallel with IGBTs and the other two diodes are in series from PFC input to the DC-link positive.

Check the diodes using a multimeter diode function to measure their threshold voltage. Diodes must bemeasured both forward bias and reverse bias condition to make sure they are satisfactory. See thefollowing pictures and table to make all the necessary measurements.

L1

L2

IGBT diodes

Series

diodes


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Diode Positive test lead Negative test lead Result

Diode 1 forward bias L1 Rectifier output 0,2-0,7VDCDiode 3 reverse bias L1 GND No valueDiode 1 reverse bias Rectifier output L1 No valueDiode 3 forward bias GND L1 0,2-0,7VDCDiode 2 forward bias L2 Rectifier output 0,2-0,7VDCDiode 4 reverse bias L2 GND No valueDiode 2 reverse bias Rectifier output L2 No valueDiode 4 forward bias GND L2 0,2-0,7VDC

GND

Rectifier output

L1

L2

L2

L11

3

2

4


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Diode group Positive test lead Negative test lead Result

Series diodes forward bias PFC input DC-link positive 0,2-0,5VDCIGBT diodes reverse bias PFC input GND No valueSeries diodes reverse bias DC-link positive PFC input No valueIGBT diodes forward bias GND PFC input 0,3-0,7VDC

4.3.1.2. IGBT

Mains supply voltage must notbe connected during the IGBT module diode measuring.

IGBT module can be tested by a multimeter when using the diode tester function. The module holds fourdiodes and if IGBT is damaged, in many cases these will be defective. They can be measured only inpairs if main transformer primary is connected, if it is removed all the four diodes can be measuredseparately.

GND

PFC input

DC-link


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Check the diode groups using the multimeter diode function to measure their threshold voltage. Diodesmust be measured both forward bias and reverse bias condition to make sure they are satisfactory. Seefollowing pictures and table to make all the necessary measurements.

IGBT 1 emitter and IGBT 2 collector are connectedvia main transformer; it is not possible to measure allthe four diodes separately without disconnecting the

transformer primary.

Maintransformerprimarywinding

GND

IGBT 1emitter

DC-link

IGBT 2 collector

1

2

IGBT 1 emitter


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IGBT Positive test lead Negative test lead Result

IGBT 1 diode + upper separatediode; forward bias condition

IGBT1 emitter/IGBT 2collector

DC-link positive 0,2-0,7VDC

IGBT 2 diode + lower separatediode; reverse bias condition IGBT1 emitter/IGBT 2collector GND No value

IGBT 1 diode + upper separatediode; reverse bias condition

DC-link positive IGBT1 emitter/IGBT2 collector

No value

IGBT 2 diode + lower separatediode; forward bias condition

GND IGBT1 emitter/IGBT2 collector

0,2-0,7VDC

If the transformer primary is disconnected, IGBT 1 emitter and IGBT 2 collector connection points can beused separately to measure diodes one by one. In this case the table must checked twice: first using theIGBT 1 emitter point only and then the IGBT 2 collector point.

4.3.1.3. Secondary rectifier

Mains supply voltage must notbe connected during the secondary rectifier diode measuring.

Use a digital multimeter to test the secondary diodes. Diodes are in groups, so it is not possible tomeasure them one by one unless they removed from the board and measured separately.

Diode Positive test lead Negative test lead Result

Forward bias Negative output terminal Positive output terminal 0,2-0,6VDCReverse bias Positive output terminal Negative output terminal No value

4.3.1.4. Voltages

The Z001 main circuit card has the DC-link voltage after the input rectifier and several auxiliary voltagesmade by the auxiliary PSU. Floating point voltage and remote control reference voltage need their own

ground points to get right values.

Note! Most voltages are in the primary side. Even touching the ground level may affect electricshock because there is up to 120VDC between the ground and protective earth.

+16VDC,C26 left side

connection point

+24VDC,V46 bottom leg

Primary GND,V62 leg on the upperside, second from left


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Reference GND,

Floating +16VDC,C56 upper connectionpoint

Floating GND,C56 bottom connection point

+12VDC,Test point on the rightside of R22

Reference ground, N3right side, third legfrom top

+390VDC,DC-link,TP4

Primary GND,TP5


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4.3.1.5. Overheat protection

Main transformer PTC is soldered to the Z001 main circuit card:

Measure the resistance: It should be less than 100 In over temperature situation PTC goes to high-resistance mode (>10k) Machine gives temperature alarm at 1,5k A broken PTC has usually hundreds of kilo ohms resistance or no value at all.

Both primary modules NTCs are integrated inside the module:

Measure the resistance, it should be between 60-15kin a cool machine (inenvironment temperature 0-40C)

While temperature rises resistance lowers and at 2kpoint the inverter stops and givesoverheat alert.

A broken NTC has usually hundreds of kilo ohms resistance, no value at all or shortcircuit.

PTC common point

Main transformer PTCresistor

NTC common point

Rectifier/PFC module NTCresistor


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4.3.2. A001 control card

Control card voltages have common ground, on the primary side. +16VDC and +24VDC PSU are located

on the Z001 card. +5VDC is made on the A001 card.

Note! Voltages are in the primary side. Even touching the ground level may affect electric shockbecause there is up to 120VDC between the primary ground and protective earth.

NTC common point

IGBT module NTC resistor

GND,S5 upper leg

+5VDCTest point between the S5switch legs. Also N3second leg from the lowerleft

+16VDC,Test point

GND,C26 left side or upper legof S5 as shown in theprevious picture


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4.3.3. Cooling fan

Cooling fan gets the power from the +24VDC line. Voltage can be measured in the X7 connector (X7-1+24VDC and X7-2 GND). Note that the cooling fan has delayed starting.

The cooling fan is installed so that the air flows from the left side plate to Z001 card. Air comes outthrough the front and the back plate grills.

4.3.4. Low voltage tests

Low voltage test may give some basic information where the fault might be. Machine should be fed fromthe MLS service power to test connection. Voltage should be 320VDC so the high voltage switch must in230VAC mode. There are no pins to fasten the PSU hook clips to, so it is a good idea to solder someduring the repair.

Once the connections are made, power can be switched on, the panel functions can be tested andauxiliary voltages measured both on the Z001 and the A001 cards (see the chapters for auxiliary voltagemeasuring on the A001 and Z001 cards).

+24VDC,R17 left side connection point

GND,C1 right side

Primary GND,X14

+320VDC test point,X22


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4.3.5. Safety tests

Safety tests are made normally, but PE conductivity test cannot be tested, because there are no outer

parts connected to PE. Do not use PE continuity test equipment with high testing current.

PE wire conductivity should be measured only by DMM with resistance function to continuity. Measurethe resistance between the main supply cable terminal and Z001 X3.

4.4. Semiconductor installation

It is a must be to use torque screwdriverwhile tightening any power components onto the heatsink. See following sections for tightening torques.

4.4.1. Rectifier/PFC module and IGBT

MinarcEvo 150 has soldered input rectifier/PFC and IGBT modules and it is not possible to change themseparately. Only reliable way to replace the module(s) is to change the whole Z001 main circuit card.

The heat sink paste should be spread on to the modules in an even layer by using fingers. Then the cardshould be immediately mounted onto the heat sink, this minimizes the possibility of any contamination(dirt etc.) getting between the components.


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The hexagonal fixing screws for the IGBT module are tightened (stage 1) to 1 Nm. And after few minutesthe module screws can be finally tightened (stage 2) to a torque of 2,0 Nm.

Once all four hexagonal screws are tightened to right torque, the module support cap screws can befastened. The idea is to support the module to the PCB with the plastic caps, instead of the componentsoldered legs. The torx screws for caps can be tightened only up to 0,5 Nm, or otherwise PCB may bend.

4.4.2. Secondary rectifier

The heat sink transfer compound should spread in an even layer onto the heat sink. Then the card shouldbe immediately mounted onto the heat sink, this minimizes the possibility of any contamination (dirt etc.)getting between the components.

The torx fixing screws in diodes are tightened to 1,2 Nm and the resistor (a smaller case than the diodes)to 0,7 Nm.

4.5. Final testing

After the machine repair and low voltage tests, it is good practice to carry out some load tests and finishwith some test welds. Only then is it possible to guarantee the machine is working correctly.

Hexagonal screw Support cap Support cap screw

Hexagonal screwsSupport cap

Support cap screw


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4.5.1. Load bank test

CC (MMA and TIG machines) curves secondary voltage can be calculated when a certain current is set:

MMA mode: 2004,022 +=IU

TIG mode:1004,0

22 +=IU

Voltage has to be set for the nominal curve to get the correct output power. E.g. when making a PTC testthe correct values must be used to meet the duty cycle specified in technical specification.

Most useful tests to be made with a load bank are to check maximum and minimum current and paneldisplay values.

The following example uses 140A so the correct voltage can be calculated using the equation below:

VA

IU

AI

6,252004,0140

2004,0

140

22

2

=+=

+=

=

Output voltage should be 25,6V.

Example: Minarc Evo 150 MMA mode load bank test, welding current 140A and output voltage 25,6V

Turn the machines main switch OFF

Connect machine to the load bank and check that there is no load added. Turn the machines main switch ON, Adjust machine current to desired level (this example uses 140A) Add some load to get the inverter operate, be fast in switching because arcing may exist

between the connection surfaces of the switch Measure load voltage by a DMM Add or decrease load to get the desired voltage

If using active load bank, instead of increasing or decreasing load, it is only necessary to select MMAnominal curve and then set the test current value on the machine. The Load follows automatically thecurrent value and the output voltage will be correct.

4.5.2. Test welding

Test welding is important for having final and reliable information, if the maintenance / repair has beenmade successfully.

In some cases a load bank test alone does not give the absolute truth if the machine is functioning

properly or not. Test welding will show if the power source and control panel are working together in anatural state.

While carrying out test welding, it is useful to test at different current settings to see if the current is rightand ignition good.

Pay attention especially to the features that were the original reason for the maintenance work.


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5. NOTES

Minarc Evo 150 Service Manual

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Transcript of Minarc Evo 150 Service Manual